In general, in case of automobiles, if a surface of glass window is polluted due to dusts or various foreign matters in the air or weather-related snow or rain, it is difficult to secure the field of vision, thus safe driving is hindered. Therefore, as means for securing the field of vision for safe driving of the driver, a wiper device for vehicle is installed which wipes out snow, rain or foreign matters etc. on the surface of glass window.
A wiper device according to a prior art comprises a blade of a predetermined length made of soft rubber for wiping out snow, rain or polluting matters while moving in close contact with the surface of glass window; a body spring coupled to upper end of the blade and having a predetermined curvature and elastic force; a resting plate coupled to the body spring at center thereof in a longitudinal direction; an adaptor coupled to the resting plate; and a longitudinal arm for delivering rotational power by connecting one end of the arm to a motor installed in the vehicle and detachably connecting the other end to the adaptor.
In this connection, if the arm is not firmly coupled to the adaptor, the arm may depart from the adaptor to thereby cause a car accidence, therefore, various arms and adaptors with increased coupling force have been recently developed, and such techniques are proposed in Korean Patent Publication No. 10-2008-0108360 (hereinafter, “cited reference 1”) titled “A Windscreen Wiper Device” and Korean Registration Patent No. 10-0692369 (hereinafter, “cited reference 2”) titled “Wiper connection device of wiper arm join a form”.
The arm according to the cited reference 1 is formed so as to wrap top portion and both lateral sides of the adaptor and is provided on upper surface of its free end portion with finger parts.
Furthermore, in the adaptor according to the cited reference 1, formed at free end portion of joint member are concave parts coupled with the finger parts of the arm, and protruding parts are formed each extending from longitudinal direction side of the joint member to lateral direction, by which parts protruding parts correspondingly formed on the arm are caught.
However, the adaptor according to the cited reference 1 has a structure wherein the finger parts of the arm are inserted in the concave parts formed on the joint member into close contact therewith and the protruding parts of the arm are supported on the protruding parts formed on side walls of the joint member, whereby the arm is coupled to the adaptor. Since the finger parts of the arm are not hook-coupled to the concave parts of the adaptor, but simply inserted in the concave parts into close contact therewith, there is a concern that the finger parts of the arm coupled to the concave parts of the adaptor can be separated from upper portion of the adaptor due to shock from the outside or centrifugal force resulting from wiping.
Furthermore, the arm according to the cited reference 2 is one of top lock type and is formed so as to wrap the upper portion and both lateral sides of the adaptor, and has assembling holes on upper plate and protruding parts formed on both side walls.
Furthermore, the adaptor according to the cited reference 2 comprises two side plates including elastic members exhibiting elasticity through elongate holes formed in both side walls and having a through hole formed in the center; a front plate including depressed groove in which upper portion of a blade is inserted; depressed part formed so as to be opened at its lower end and provided through a plurality of ribs; and a upper plate having a button formed on its upper portion and coupled to the assembling hole of the arm.
In the case of such an adaptor according to the cited reference 2, the arm is coupled to the adaptor by coupling the button protrudingly formed on the upper plate to the assembling hole of the arm. Namely, the arm is placed so as to cover upper portion of the adaptor in such a way that the protruding part of the arm is brought into close contact with both sides of the adaptor, and thereafter the button of the adaptor is inserted in the assembling hole of the arm, whereby the arm is coupled to the adaptor.
However, since the adaptor according to the cited reference 2 is coupled with the arm only by using the button formed on the upper plate, portion for coupling the arm with the adaptor is not sufficient, the coupling force is weak, and since both sides of the adaptor is formed so as to exhibit elasticity, there is a concern that the arm can be separated from the adaptor due to shock from the outside or centrifugal force resulting from wiping.
Therefore, in order to solve the above-mentioned problems, the applicant has filed an application relating to an adaptor to which an arm with hook is applicable. Such an adaptor is proposed in Korean Registration Patent No. 10-0891195 (hereinafter, “cited reference 3”) titled “Automobile wiper-blade”. However, the adaptor according to the cited reference 3 should have an auxiliary cap in addition to the adaptor in order to increase a coupling force for coupling the arm with the adaptor, which results in a problem that the structure becomes complicated and production cost is increased and inconvenience of users is caused.